Technical Field
The invention relates to an anchor. The invention further relates to a tensioning device, a wind energy plant and a method for tensioning tensile cords on an anchor.
Description of the Related Art
In order to reinforce pre-stressed concrete constructions, more particularly in the field of pre-stressed concrete towers, such as for example a tower on a wind energy plant, tensioning wires are used, which by applying a tensile force create tensioning and strengthening of the structure; particularly in the case of a pre-stressed concrete tower of a wind energy plant made up of a number of tower segments, one individual tower segment or a first and a second tower segment or the number of tower segments per se are set under tensile stress individually or with one another. In general a tensioning device is designed for attachment to a construction and for holding tensile cords on a structure such as by way of example the tower of a wind energy plant. In the case of wind energy plants, the fixed connection is achieved for example by bringing together the tensioning or tensile wires or a rod or the like singly or in bundles to form one tensile cord and are anchored to the foundation base; an anchor of the tensioning device, here called a tension anchor, normally serves for this purpose.
The tension anchor is connected via one or more tensile cords to a fixed anchor at a different point of the structure, and by applying tensile stress between the tension anchor and the fixed anchor can produce the tensile stress on a component part or between the component parts of a structure, such as by way of example tower segments of a tower. A tension anchor differs from a fixed anchor in that the tension anchor has engagement means for fitting a tensioning tool, more particularly a tension anchor is designed to move a tensile cord against the tension anchor to thus set this under tensile stress. A fixed anchor has on the other hand no function means for changing or increasing the tensile stress of a tensile cord; rather a fixed anchor serves to be fixed at a suitable point of the structure in concrete or on a concrete component, in order to hold one or more tensile cords on the fixed anchor.
Anchoring the tensioning device or the tensile cords on the tension anchor is preferably carried out by fastening the tensioned tension wires by way of example by means of a previously explained tension anchor (also called a tensile anchor) on for example a roof of the tower basement. This fastening is carried out typically by passing the tension wires through a corresponding opening in the basement roof when working in the tower basement, wherein the wires are then tensioned by a hydraulic stamping device and then fastened against the roof by means of a tension anchor.
From DE 100 31 683 A1 a pre-stressed concrete tower is known by way of example for a wind energy plant with a foundation base, a tower made substantially of concrete and at least one cable-like tensioned steel element for tensioning the tower. It is thereby proposed that the tensioned steel element is fixed by means of tension pockets arranged on the tower.
EP 1 303 676 B1 discloses a tower of a wind energy plant having a plurality of prefabricated segments arranged one on the other and tensioned together by means of tensioning elements wherein each prefabricated segment has a ring element. In order to guide tension wires or such tensile cords in an improved way at the joining points of the individual tower segments it is proposed that one ring element has a guide device for guiding a tension wire at the transitions between the prefabricated segments wherein the guide device has a tubular section at one end.
An anchoring device for tensile members having an anchorage body through which the tension member is guided is described in general in EP 0 949 389 B1 and has two anchor wedges which are arranged around the tensile member and by means of which the tensile member is fixed in the anchorage body. A protection element is thereby provided which is arranged between the anchor wedges and the tensile member so that the force enters the tensile member indirectly via the protection element. The surfaces of the anchor parts which are in contact with the protection element and/or the surface of the protection element which is in contact with the anchor parts is provided with recesses.
An external tensioning member mentioned at the beginning and including a tensile member which is encased by a flexible tube whose hollow cavities are filled after tensioning with a hardening mass, is known from DE 198 58 001. A fixed anchor called an end anchorage is described therein where the tension elements of a tensioning member are anchored on a perforated disc by means of fastening elements formed as a wedge. The tension elements each run inside an anchorage area inside a small transition tube which has at one end an external thread with which it is screwed into an associated threaded bore in an intermediate plate. At the other end each small transition tube is inserted fixedly into an associated bore of a sealing disc. The bore has a narrow area which closely surrounds the tension element which is passing through same. At a distance from the aforementioned sealing disc there is a second sealing disc with narrow bores wherein the internal space between the two sealing discs corresponds at least to the intended re-tensioning path.
This design enables a comparatively reliable fixed anchor to be formed which is moreover in a position to protect a tension element against damp. An anchor of this kind can however still be further improved.
DE 15 59 526 discloses a fastening element for an anchor as an anchor part which touches the wires and is provided with recesses which adapt to the shape and the path of the wires.
From DE 92 06 827 a wedge anchor for cords or wires has become known having at least one substantially frusto-conical wedge including wedge segments for inserting in a conical bore of an anchor body.
A drawback of the previous designs of an anchor lies in the fact that these seek to overcome the sealing problems in a way which is comparatively expensive and although they may be comparatively secure they do however require a large structural space. This structural space is however only available in a limited amount particularly in the case of industrial towers. It is desirable to design an anchor and a method for attaching an anchor in a simpler but nevertheless secure way.
The German Patent and Trade Mark Office has searched in the priority application the following prior art: DE 33 39 125 C2, DE 34 27 901 A1, DE 101 26 912 A1, DE 198 33 273 A1, U.S. Pat. No. 4,405,114 A, U.S. Pat. No. 5,469,677 A, EP 0 197 912 A2, EP 1 505 223 A1, EP 2 339 094 A1, WO 98/41709 A1.